The present invention relates to electrostatographic printing apparatus and more particularly to an apparatus for detecting whether a removable imaging member is installed in the printing apparatus in a predetermined operative position.
In an electrostatographic reproducing apparatus commonly in use today, a photoconductive insulating member is typically charged to uniform potential and thereafter exposed to a light image of an original document to be reproduced. The exposure discharges the photoconductive insulating surface in exposed or background areas and creates an electrostatic latent image on the member which corresponds to the image areas contained within the usual document. Subsequently, the electrostatic latent image on the photoconductive insulating surface is made visible by developing the image with developing powder referred to in the art as toner. Most development systems employ a developer material which comprises both charged carrier particles and charged toner particles which triboelectrically adhere to the carrier particles. During development the toner particles are attracted from the carrier particles by the charge pattern of the image areas in the photoconductive insulating area to form a powder image on the photoconductive area. This image may subsequently be transferred to a support surface such as copy paper to which it may be permanently affixed by heating or by the application of pressure.
Many commercial applications of the above employ a modular concept for the various processing stations. For example, the imaging member, developer assembly and cleaner assembly may be combined in a single unit or cartridge which has a limited life at the end of which it may be discarded and replaced with a new unit or cartridge. Alternatively, a charging device may be added to the unit or the unit may contain any of the developer, cleaner, and imaging member.